# Copyright (c) 2007-2009 Jorge Ortiz Romo <jortizromo@gmail.com>
#                         Freymam Vallejo Cuero <freturn@gmail.com>
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.

'''
Created on Dec 7, 2009

@author: Freymam
'''

# Imports
from __future__ import division


def network_density(graph):
    """
    network density

    @type graph:  digraph
    @param graph: Digraph.

    @rtype: float.
    @return: float between 0 and 1, if all the lines are present, then all nodes are adjacent and the graph is said complete.
    """
    
    # Calculate max edges on the graph.
    maximum_edges = graph.__len__()*(graph.__len__() - 1)/2

    #Count edges on the graph
    edges = len(graph.edges())/2

    #Calculate Density of the graph and return it.    
    density = edges/maximum_edges
    
    return density

